The principal components of a skeletal system, for example a human skeletal system, include bones which comprise the framework for the body, cartilage which forms the connecting and supporting structures among the bones, and ligaments which bind the bones together. When a ligament becomes detached from a bone, for example due to an athletic or other injury, it is often desirable to reattach the ligament to the bone.
Ligaments and other soft tissue (e.g., tendons) may be reattached to a bone in a number of different ways. For example, Goble et al. U.S. Pat. No. 5,013,316, issued May 7, 1991, discloses a soft tissue anchor comprising a footing stud that includes a drill and followed by self tapping threads, wherein the footing stud is arranged for turning and tapping into a bone mass. A longitudinal hole is disposed within the footing stud and is configured to receive and retain therein a tack which includes an undersurface comprising spikes for engaging and penetrating a ligament. When the tack is urged into the bore of the footing stud, the spikes engage the soft tissue and maintain it in intimate contact with the bone.
Goble et al. U.S. Pat. No. 4,738,255, issued Apr. 19, 1989, discloses a suture anchor system that includes a drill and guide arrangement for drilling an opening into a bone mass which is outwardly flared to accommodate a suture anchor dispensed from an applicator, which suture anchor is configured to be expanded within the bone mass to secure the anchor within the undersurface of the bone. As tension is applied to the suture, the anchor remains underneath the surface of the bone.
Hayhurst et al. U.S. Pat. No. 5,037,422, issued Aug. 6, 1991, discloses a bone anchor which comprises an elongated, thimble-shaped body having slots extending lengthwise through the body and a suture receiving opening provided in the tip of the body. At least one ridge or barb extends outwardly from the exterior of the body and defines an edge which is adapted to be lodged in the wall of a bore formed in the bone mass. The tip of the anchor is configured to be inserted into a bore in the bone, such that when tension is applied to the sutures, the resilient walls of the anchor are flared outwardly, locking the anchor into the bore within the bone.
Paulos et al. U.S. Pat. No. 4,988,351, issued Jan. 29, 1991, discloses a soft tissue washer for use with a bone screw for attaching soft tissue to a bone. The washer comprises a plurality of sharp pins extending from the distal face of the washer, there being a plurality of posts interposed among the pins also extending from the distal face of the washer. The washer comprises a central bore for receiving a bone screw therewithin. As the bone screw is tightened into the bone, the sharp pins engage the soft tissue to retain the tissue in intimate contact with the bone; the posts limit the degree of penetration of the pins into the bone such that the distal face of the washer is maintained a predetermined distance from the bone surface, such that the soft tissue is maintained between the distal face of the washer and the bone.
Anspach, Jr. U.S. Pat. No. 5,102,421, issued Apr. 7, 1992, discloses a suture anchor in the form of a rivet having three radially extended flanges configured for penetration into a bone. A cylindrical extension projects rearwardly from the flanges and has a suture secured thereto. A plurality of spiral grooves are formed within the flanges to facilitate turning of the anchor as it is tapped into a bone mass. The aforementioned grooves also serve to define a series of serrations therebetween, which serrations aid in preventing withdrawal of the anchor.
Other known devices attempt to dispose the suture anchor site wholly within or underneath the bone surface, such as the "Quick Anchor".TM. bone anchor manufactured by Mitek Surgical Products, Inc. of Norwood, Mass. The Mitek Quick Anchor bone anchor is configured to be dropped within a bore of a bone mass using a collar device, functioning to retain expandable wings in a retracted position during insertion. Once the device is inserted into the bone cavity, the wings expand, much like a grappling hook, to prevent withdrawal of the device. Presently known suture anchor devices are unsatisfactory in several respects. For example, the suture attachment sites of many known devices are of sharp or otherwise irregular construction, tending to irritate adjacent tissue. Moreover, many known devices tend to migrate within the bone mass, which may result in the device becoming lodged within a joint. In addition, presently known devices require cumbersome tools and accessories for inserting the device, for example devices which require turning or screwing during insertion.
A suture anchor is thus needed which overcomes the short-comings of the prior art.